Many liquids are transported via subterranean/underwater pipelines. When a leakage crack or hole forms in the pipeline, the liquid leaks therefrom. Often, it takes a long time to detect a leakage and yet longer to locate the leakage site. Oil, gas and water transportation are thus subject to tremendous losses due to pipeline leakage.
There is thus a need to maintain and seal subterranean/underwater pipelines quickly in situ.
Several patent publications in the field include U.S. Pat. No. 3,523,826A which relates to a process for cleaning a piping system which is characterized by circulating in, and through said system a thixotropic emulsion having a hi.-h volume ratio of internal phase to external phase, the emulsion having an emulsifying agent, an emulsifiable oil and a non-oil, the emulsion being an oil-in-non-oil or a non-oil-in-oil emulsion, the internal phase of said emulsion being present in said emulsion in an amount of at least 80% by volume of the emulsion, said emulsion having the characteristics of a solid when at rest and the characteristics of a liquid when a force is exerted on it, said emulsion tending to be non-adhesive, said emulsion having a critical shear point sufficient to permit pumping at high rates, and said emulsion having an apparent rest viscosity greater than about 1000 cps.
U.S. Pat. No. 4,216,026 describes a method for removing fluid and/or particulate debris from a pipeline, a Bingham plastic fluid plug is passed through a pipeline and the fluid and/or debris are collected by the plug. The plug is pushed through the pipeline with a scraper which in turn may be pushed by liquid or gas pressure. Where the fluid to be removed is water, the Bingham plastic fluid plug employed preferably is a composition of water and a xanthan gum, and the gum may be cross-linked with a multivalent metal. Where the fluid to be removed is a hydrocarbon, the Bingham plastic fluid plug employed preferably is a composition of a mineral oil and an organo-modified smectite, and may also include a particulate filler such as powdered coal.
U.S. Pat. No. 4,252,465A describes a gel plug, which is employed during construction of an offshore pipeline to separate a gas-filled portion of the pipeline from a water-flooded portion, and to facilitate control and movement of the gas/gel plug/water interface as desired to assist in construction operations.
U.S. Pat. No. 4,254,559A relates to an interior surface of a pipeline being dried by sequentially passing through the pipeline (a) an aqueous cross-linked gelled pig, (b) a fluid mobility buffer comprising a non-cross-linked gelled ankanol of from one to three carbon atoms, (c) a dessicating amount of a liquid alkanol from one to three carbon atoms. For example, a pipeline was dried by sequentially passing through it (a) a borate cross-linked hydroxypropyl guar gum pig, (b) a fluid mobility buffer comprising methanol thickened with hydroxypropyl cellulose, and (c) methanol.
U.S. Pat. No. 4,379,722 discloses a gel plug of mineral oil, organo-modified smectite, and a particulate filler such as powdered coal, or a gel plug of mineral oil and organo-modified smectite is employed during construction of an off-shore pipeline to separate a gas-filled portion of the pipeline from a water-flooded portion, and to facilitate control and movement of a gas/gel plug/water interface as desired to assist in construction operations.
U.S. Pat. No. 4,416,703 describes a method to remove particulate debris from a pipeline, a plug train including at least one gel plug having debris entraining characteristics and at least one pseudoplastic plug is passed through a pipeline and the debris is collected by the gel plug. The gel plug is pushed through the pipeline with a scraper which in turn may be pushed by liquid or gas pressure.
U.S. Pat. No. 4,321,968A discloses gelled compositions comprising carboxymethylhydroxyethyl cellulose in aqueous brine solutions, which are gelled by the addition of an alkaline earth metal hydroxide such as calcium hydroxide. The gelled compositions have utility as water diversion agents, pusher fluids, fracturing fluids, drilling muds, work-over fluids, and completion fluids.
U.S. Pat. No. 5,346,339A provides a method of cleaning a pipeline using a gel pig of a graft copolymer of a hydroxyalkyl cellulose prepared by a redox reaction with vinyl phosphonic acid. The gel pig is formed by hydrating the graft copolymer in an aqueous liquid. The gel pig is crosslinked by the addition of a Lewis base or Bronsted-Lowry base, to the gel in an amount sufficient to initiate crosslinking of the graft copolymer. Contaminants entrained in the crosslinked gel pig during the cleaning process may be separated by the addition of a pH reducing agent to the pig whereby the viscosity of the gel is caused to decrease. The gel may be used for further cleaning after contaminant separation by addition of an additional quantity of the Lewis base or Bronsted-Lowry base.
US2003109385A provides a process for treating a hydrocarbon-bearing formation having at least one hydrocarbon bearing zone and at least one water bearing zone wherein the ratio of the permeability of the hydrocarbon bearing zone(s) to the permeability of the water bearing zone(s) is in the range of from 1:20 to 3:1 comprising: a) sequentially injecting into the formation: (i) an aqueous polymer solution comprising 0.01 to 0.5 weight percent of a water-soluble polymer having from 0.01 to 7.5 mole percent of crosslinkable carboxylate and/or phosphonate groups and a molecular weight in the range of 250,000 to 12,000,000; and (ii) an aqueous solution of a crosslinking agent; and b) back-producing the aqueous polymer solution over the crosslinking agent so that the polymer crosslinks within the formation to form a gel which is collapsible to allow hydrocarbon flow.
US2008277112A discloses a method for treating a portion of a subterranean formation or a propellant pack is provided. In general, the method comprises the steps of: (A) forming or providing a treatment fluid comprising: (i) water; (ii) a chelating agent capable of forming a heterocyclic ring that contains a metal ion attached to at least two nonmetal ions; and (iii) a viscosity-increasing agent; and (B) introducing the treatment fluid into the wellbore under sufficient pressure to force the treatment fluid into the matrix of the formation or the propellant pack.
WO2008081441 describes a method of repairing leakage in pipelines comprising the steps of forming a first and second openings in the pipeline upstream and downstream, respectively, of the leakage location, inserting through the first opening a first body, filling the space arrear of the first body (C1) with a first viscous sealing material (M1), inserting through the first opening a second body (C2) arrear of the first viscous sealing material (M1) compressing the first sealing material by applying a pressure against the first and the second bodies (C1, C2) in opposite directions, causing the first and second bodies (C1, C2) and the compressed first sealing material (M1) to move in unison in the direction of the second opening, and retrieving the first and second bodies (C1, C2). Preferably, the method is performed using three bodies (C1, C2, C3) and two sealing materials (M1, M2).
However, there are still many types of pipeline leakages, which cannot be cured using the aforementioned prior art materials and methods. There thus remains an urgent need to develop systems and methods for curing pipeline leakages.